1 Field of the Invention
This invention relates to typefaces or fonts for typographic apparatus used in desktop publishing (DTP) and the like. More particularly, the invention relates to a kerning method for diminishing space between characters and to a typographic apparatus utilizing this method.
2 Description of the Related Art
In the computer-based electronic typography today, characters handled by typographic apparatus, regardless of the type of characters such as kana, kanji, etc., have faces fitting in frames of a predetermined size. First, components of a character will be described with reference to a schematic view shown in FIG. 1. As used in the following description, the term "characters" refers to numerals and varied signs as well as letters in a narrow sense (such as alphabets and the like) which are used in forming ordinary sentences and words.
The schematic view shows a makeup of kana "&lt;", by way of example.
The configuration of the character is enclosed in an "imaginary body" IB which is a rectangular frame (character frame) representing a minimum character positioning unit. The imaginary body IB has a horizontal length X providing a "character width", and a vertical length Y providing a "character height". Generally, the character width X and the character height Y have the same value.
The imaginary body IB includes a "face" F placed therein which represents a configuration of a character. The face F is composed of dot data based on a combination of dots, or vector data mathematically depicting a shape. The face F has an outermost contour thereof enclosed in a rectangular frame called bounding box (face frame) BB. The bounding box BB has a horizontal length W providing a "face width", and a vertical length H providing a "face height". A comination of face width W and face height H is referred to hereinafter as a face size.
As shown, the difference (space width) between the face width W of the face F disposed inside the imaginary body IB and the character width X of the imaginary body IB provides a front space "a" and a rear space "b". The difference between the face height H and the character height Y provides an upper space "c" and a lower space "d". These spaces are variable with the size and shape of face F enclosed in the imaginary body IB, i.e. variable from character to character.
The bounding box BB sometimes refers to a rectangular frame including suitable margins (side bearings) around the face F. In the following description, the bounding box is regarded as including no such side bearings unless otherwise noted. In the case of the European alphabets, usually, the spaces "a" to "d" are not provided between the imaginary body and bounding box, that is, the imaginary body is identical to the bounding box BB. However, for expediency of description, the spaces "a" to "d" are regarded as being provided for the European alphabets also. This poses no inconvenience in understanding the present invention since the spaces "a" to "d" may be described as zero if no such spaces are provided.
In arranging characters of a character string in a predetermined direction, an object character may be positionally adjusted or kerned relative to an adjacent reference character already fixed in place. In a most typical example of such kerning methods (which is called a pair kerning method), space reduction amounts for predetermined character pairs are provided in the form of a table, a space reduction amount for each pair of a reference character and an object character is read from the table, and the characters are arranged according to the space reduction amount.
In another kerning method, a dot facing space between dot partterns of two character faces is determined in a direction of character arrangement. The characters are then arranged so that the dot facing space agrees with a desired facing space. In a different kerning method developed recently, a facing space between two character faces is computed in a direction of character arrangement. The characters are then arranged so that the facing space agrees with a designated facing space.
The conventional kerning methods noted above have the following disadvantages.
Where the character string includes a small character or sign such as ".multidot." (middle dot) or "." (period), the preceding character (reference character) is too close to ".multidot." or ".", or the succeeding character (object character) comes too close to ".multidot." or ".", thereby impairing visual recognition and appearance. Particularly where the reference character is "", for example, an object character "." may come too close to "" to the detriment of visual recognition and appearance.